Thursday, 25 July 2013

Adventures in CNC - Part 2

Buyer Beware

The world of CNC, once a tool only available to large industry, is now making its way into the basement shops of hobbyists in a big way. CNC manufacturers are scrambling to produce lower cost machines for this expanding market. The trick is to figure out the difference between 'low cost' and 'cheap'.

Hobby CNC is still a relatively niche market, and due to the complexity and cost of these systems, most users tend to be technically inclined folks who love spending hours fine-tuning an extra thousandth of an inch accuracy out of their machines. Because of this complexity, it is difficult for large tool manufactures to produce a 'Home Depot friendly' CNC solution. This has allowed a cottage industry of small manufacturers to spring up to fill the void. The products of these small shops will most likely not be reviewed in many mainstream publications so you will need to do a lot off digging to see if a given system meets your needs.

When shopping for your machine, you should have a clear idea of the type of work you need it to perform and a clearer idea of your budget. Then scour the internet for every last shred of information you can find. If you can find reviews from actual owners, all the better. When comparing prices, it is important to make a list of extra items you will need to buy to get things running. Sometimes a seemingly good deal will cost you more in the long run.

The Bottom Line

For my CNC router system, I came up with this list of requirements to help narrow down the field.

I want to keep the budget at approximately $5000

I want the size to be large enough to at least handle a full sized guitar or bass body

I would like the machine to be somewhat upgradeable (Software, Cutting Tools, etc..)

So Many Choices

Here are some of the machines I have been looking at and the thought process I used when evaluating them:

PROS:
Shopbot is a well respected CNC manufacturer. I was hard pressed to
find any negative reviews of their products. The also have a great
support community. It is a robustly built machine using industrial grade parts. The
machine comes mostly assembled and includes a specifically designed
software suite which will allow the newbie to get up and running fast.
The base model ($5000) comes with a router mount but can be upgraded to a
industrial spindle for $1600 more.

CONS: First the size. The cutting area of the machine is 24" x 18" x 3" which may be a little small for some of the projects I have in mind. Then there is the cost. $5000 plus god knows how much extra shipping and duty to Canada is steep for a small desktop machine.

PROS: This is another ready built - 'turn-key' solution which means I would be up and running quickly and at $4700, it just fits within my budget. The General Tool line is distributed by some local tool stores so I could pick this machine up avoiding shipping fees. It comes with a Spindle as standard and includes software. General tool is a reputable manufacturer so I am confident that service and support would be adequate.

CONS: The iCarver has a somewhat smaller work area at 15" x 20" x 4" which may make it unsuitable for my applications. The iCarver uses a Proprietary Control box instead of a external PC. The final g-code files are transferred to the box via USB memory stick and run from there. While his does make the setup easier, it seems like it would limit the flexibility that an external control PC provides. The construction of the machine seems to be geared towards light-duty hobby use and the spindle is limited to 1/4" bits. It is also not upgradeable if you wanted some better motors or spindle in the future.

EXTRAS REQUIRED: While the unit does come with ArtCAM Express as it's CAM software, it is a bare-bones version. ArtCAM allows you to buy extra modules to add functionality to their software. These modules range in price from $150 to $800 so you can see how the price can add up.

PROS: At $3800, this is one of the more affordable CNC packages out there. It comes with VCarve PRO and Cut 3D software which is a nice package that will handle most jobs. It boasts a 25" x 25" x 5" cutting capacity which is slightly larger than its competition.

CONS: No spindle option, it is designed for handheld router use only. Some of the earlier models were reported to suffer from inaccuracy due to frame flexing although I have heard that this may have been improved in later models. This is definitely a light duty machine. Rockler only ships this machine to the continental United States so international buyers will have to find another supplier.

PROS: XZero is a small local CNC builder in my area. I came across their products while reading some product reviews on the CNC Zone Forums. XZero seemes to favor over engineering their products using custom machined aluminum parts and high quality Thomson rails. This is one beefy machine for the price. The basic frame for their lower cost Viper model starts at $2400 for the smallest 30 x 24 x 6 inch footprint but can be sized up to 30 x 48 x 6 for an extra $350. It can be outfitted with mounting brackets for a Spindle or Router. At present, the Viper XZ comes included with 270oz motors, motor drivers, a 48V power supply, and a parallel port breakout card (I'm not sure if this is a limited time offer).

CONS: Since this is a true DIY kit machine, what you save on the initial purchase price you are going to pay for in sweat. You will also need to factor in the cost of software and miscellaneous extras to get a true cost estimate. Also, since this is a small company, long term support may be limited.